We need oxygen to survive, and every dream of oxygen starvation or suffocation probably symbolises a lack at psychological or intellectual level. Oxygen can express energy and vitality of the dreamer.
If one suffered in the dream from oxygen starvation, one had crept away either too deeply under the cover, or had meant the dream that awake-I needs more fresh air – in the literal like transferred sense.
Oxygen is the elixir of life. If it is supplied to one, these new impulses and new energy mean for the soul.